Interaction between human polymorphonuclear leucocytes and Staphylococcus aureus in the presence and absence of opsonins.

Phagocytosis of Staphylococcus aureus by human polymorphonuclear leucocytes (PMN) in the presence and absence of opsonins was studied with an assay which allows interaction between PMN and bacteria on a surface. The kinetics of uptake, the activity of the metabolic burst, and the degranulation during phagocytosis of opsonized and unopsonized bacteria were compared. Uptake of unopsonized S. aureus proceeded at a slower rate, but unopsonized staphylococci induced metabolic activity and degranulation in the PMN to the same extent as opsonized bacteria. Treatment of PMN with a metabolic inhibitor (2-deoxy-D-glucose) or with an inhibitor of microfilament function (cytochalasin B) totally inhibited the capacity of PMN to ingest unopsonized S. aureus, whereas uptake of opsonized bacteria was much less affected. Treatment of the PMN with pronase prevented uptake of unopsonized bacteria, but had no effect on the uptake of opsonized bacteria. Uptake was not inhibited by mannose. Recognition of S. aureus by the PMN was not dependent on the presence of the cell wall components protein A or teichoic acid. The presence of a capsule inhibited uptake.     

Effects of selective phosphodiesterase inhibitors on the polymorphonuclear leukocyte respiratory burst

Modulation of the human polymorphonuclear leukocyte (PMN) respiratory burst by selective cyclic 3',5' adenosine monophosphate (cAMP) phosphodiesterase (PDE) inhibitors was studied with respect to PDE isozyme characteristics. Zaprinast, an inhibitor of a cyclic guanosine monophosphate (cGMP)-specific PDE (PDE I), at concentrations up to 100 mumol/L, had no significant effect on the respiratory burst. Milrinone and imazodan, inhibitors of cAMP-metabolizing, cGMP-sensitive PDE (PDE III), reduced the respiratory burst to 60% of control magnitude but only had significant effects when they were introduced at high (100 mumol/L) concentrations. In contrast, rolipram and RO 20-1724, inhibitors of a cAMP-metabolizing, cGMP-insensitive PDE (PDE IV), had significant effects at low concentrations (0.1 mumol/L) and caused marked reduction of the respiratory burst at higher concentrations (25% of control at 10 mumol/L). The selective PDE IV inhibitors significantly potentiated PMN inhibition by isoproterenol. Diethylaminoethyl (DEAE)-Sepharose chromatography demonstrated a predominant PDE isozyme with high affinity and selectivity for cAMP that was insensitive to cGMP and was completely inhibited by rolipram, a PDE IV inhibitor. These results are consistent with the conclusion that the PMN respiratory burst is inhibited by an elevation of cAMP induced by PDE IV inhibition.     

中性粒细胞对洗涤血小板聚集功能的影响

目的:观察非激活或激活的中性粒细胞(PMN)对洗涤血小板聚集功能的影响。方法:采用Born方法测定血小板聚集功能。结果:非激活的PMN(5×10⁹cells/L)上清液对ADP和花生四烯酸(AA)诱导的血小板聚集具有显著抑制作用,阿司匹林可增强这种抑制作用;肉豆寇佛波醇(fMLP)及血小板活化因子(PAF)激活的PMN悬液或其上清液均能活化血小板聚集,且PMN悬液的诱聚作用比其上清液更强;阿司匹林对fMLP或PAF激活的PMN悬液或其上清液均无明显抑制作用。结论:不同状态(非激活或激活状态)的PMN对正常血小板的反应性表现出完全相反的作用,即非激活的PMN抑制血小板反应性,而激活的PMN则具有促血小板活化聚集作用。     

Depression of human polymorphonuclear leucocyte function by anti-malarial drugs.

The effect of the anti-malarial drugs quinine, chloroquine, pyrimethamine, mefloquine and quinacrine on human polymorphonuclear leucocyte (PMN) function was examined in vitro. In general, all drugs had their greatest effect on PMN iodination reaction and locomotion, intermediate effects on PMN hexose-monophosphate shunt activity, and least effect on PMN adherence. The most potent of these were pyrimethamine and mefloquine. The PMN iodination reaction and locomotion were inhibited between 0.5-1 microgram/ml (congruent to 2-4 X 10(-6) M) pyrimethamine and 1-4 micrograms/ml (congruent to 0.25-1 X 10(-5) M) mefloquine. The study demonstrates that anti-malarial drugs depress PMN functions associated with antimicrobial activity of the cell.     

Toxicity of phorbol myristate acetate-stimulated polymorphonuclear neutrophils against rat hepatocytes. Demonstration and mechanism

Human polymorphonuclear neutrophils (PMN), when exposed to soluble or particulate stimuli, can destroy various types of cells. The purpose of the present work was to investigate the toxicity of phorbol myristate acetate (PMA)-stimulated PMN against hepatocytes. Neutrophils were incubated in basal conditions or after stimulation by 100 ng/ml PMA in the presence of rat hepatocytes isolated by collagenase digestion. Cytotoxicity was quantified by the percentage of alanine aminotransferase (ALAT) activity released by hepatocytes in the culture medium. Whereas unstimulated PMN had only minor effects, PMA-stimulated PMN induced, after a 16-hour incubation, a 29.5% ALAT activity release at a PMN/hepatocyte ratio of 20/1. At the same ratio, stimulated PMN induced a 1.5% and a 16.6% ALAT activity release at 1 and 4 hours, respectively. At 1 hour, electron microscopy showed intimate contacts between PMN and hepatocytes; hepatocytes appeared morphologically normal. Hepatocytic lesions were moderate at 4 hours and marked at 16 hours. Neutrophil-induced hepatocyte toxicity could not be explained by the production of reactive oxygen intermediates since: (a) hepatocyte toxicity was not prevented by either superoxide dismutase or by catalase; (b) PMN obtained from a subject with chronic granulomatous disease were as toxic as PMN obtained from a normal subject. By contrast, a proteinase-mediated mechanism could be implicated since: (a) the supernatant of stimulated PMN induced a 45.9% ALAT activity release, after 16 hours of incubation; (b) three neutral proteinase inhibitors (i.e., alpha 1-proteinase inhibitor, phenylmethylsulfonylfluoride, soybean trypsin inhibitor) as well as fetal calf serum decreased this toxic effect by 82, 86, 81 and 70%, respectively. These inhibitors had no or minor protective effect on the toxicity of stimulated PMN coincubated with hepatocytes. This could be explained by the existence of intimate contacts between PMN and hepatocytes impeding the action of antiproteinases. Our results suggest that PMA-stimulated PMN can damage hepatocytes through the release of proteinases and that the existence of close contacts between PMN and hepatocytes might play a major role in this toxic effect.     

Opposite effects of human monocytes, macrophages, and polymorphonuclear neutrophils on replication of Blastomyces dermatitidis in vitro.

The purpose of this study was to determine the effects of human monocytes, macrophages, and polymorphonuclear neutrophils (PMN) on the fungal pathogen Blastomyces dermatitidis in vitro. Peripheral blood monocyte monolayers significantly inhibited the replication of a virulent strain (V) and an avirulent strain (AV) of B. dermatitidis by 35 and 28%, respectively. Macrophage monolayers, derived from monocytes by in vitro culturing for 9 days, also inhibited the replication of V and AV in 24-h cocultures; in 72-h cocultures, the inhibition was increased (85 and 88%, respectively). By contrast, PMN stimulated the replication of V and AV in 24-h cocultures (i.e., 45%; AV, 18%) and in 72-h cocultures (V, 68%; AV, 65%). No effect was observed in 2-h cocultures of PMN and B. dermatitidis, even though Candida albicans was killed by PMN in concurrent experiments. PMN stimulated replication of V in a dose-dependent manner, and viability of PMN was not a requirement for the achievement of this effect. These results indicate that monocytes and macrophages significantly inhibited the replication of B. dermatitidis, whereas PMN had an opposite effect. Our findings raise the possibility that these phagocytic cells may have similar opposing effects on the replication of B. dermatitidis in vivo.     

Inhibition of the in vitro growth of plasmodium falciparum by human polymorphonuclear neutrophil leucocytes

Polymorphonuclear neutrophil leucocytes (PMN) from children with acute Plasmodium falciparum malaria significantly inhibited parasite growth in homologous and in non-immune sera. Phagocytosis of schizonts in vitro was observed. PMN from uninfected children and uninfected adults had no effect on parasite growth.     

Modulation of human polymorphonuclear leukocyte function by the flavonoid silybin

The effect in vitro of the naturally occurring flavonoid silybin on human polymorphonuclear leukocyte (PMN) functions has been studied. Preincubation of PMNs for 10 min at 37 degrees C with silybin inhibited, in a dose-dependent way, the luminol-enhanced chemiluminescence (CL) generated by stimulated cells without affecting the non-enhanced CL or superoxide anion production evaluated by the cytochrome C reduction assay. No significant effect of silybin on PMN phagocytic or chemotactic activities were found. Silybin did not absorb light at the wavelength of luminol-enhanced CL and was not toxic to PMNs at the concentrations used. Catalase, a scavenger of H2O2, inhibited luminol-enhanced CL to a similar degree as silybin; moreover, when incubated together with PMNs, silybin and catalase did not produce an additive inhibition of CL. On the contrary, the simultaneous addition of silybin and sodium azide, an inhibitor of myeloperoxidase, further increased inhibition over that seen with azide alone. These results suggest that inhibition of H2O2 may be the mechanism by which silybin inhibits the luminol-enhanced CL generated by stimulated PMNs. Such results indicate a possible anti-inflammatory activity for silybin even if their clinical relevance remains to be elucidated.     

Effects of nicotine on the functions of human polymorphonuclear leukocytes in vitro

Effects of nicotine on migration, extracellular release of lysosomal enzymes, and superoxide anion (O-2) production of human polymorphonuclear leukocytes (PMN) were studied. Nicotine (5 X 10(-6) to 5 X 10(-4) M) had no effect on random migration, chemotaxis to fMet-Leu-Phe, nor on chemokinesis induced by fMet-Leu-Phe. Nicotine, however, inhibited both extracellular release of lysosomal enzymes from PMN and O-2 production of PMN, both of which were induced by fMet-Leu-Phe and cytochalasin B. The inhibition of enzyme release and O-2 production by nicotine was not affected by atropine, hexamethonium, or acetyl beta-methylcholine, suggesting a direct action of nicotine on PMN functions. It is presumed that nicotine does not affect PMN migration to inflammatory sites, but inhibits the microbicidal functions of PMN. Exposure to PMN to nicotine introduced into the body by smoking could suppress their functions. This might result in harmful influences on the host defense mechanism, including antitumor function.     

Interleukin-12 production by human polymorphonuclear leukocytes

Human polymorphonuclear leukocytes (PMN) stimulated by lipopolysaccharide (LPS) produce interleukin-12 (IL-12). Both the free IL-12 p40 chain and minute amounts of the biologically active IL-12 p70 heterodimers are produced by PMN. Interferon-γ (IFN-γ) enhanced the LPS-induced secretion of both the free IL-12 p40 chain and the p70 heterodimer by approximately fivefold. As observed for other IL-12-producing cell types, the ratio of free p40 chain to p70 heterodimer secreted by LPS-stimulated PMN was approximately 20:1. LPS induced a 100-fold increase of IL-12 p40 mRNA, but had minimal effect on p35 mRNA accumulation, IFN-γ enhanced the LPS-induced accumulation of p40 mRNA and directly induced a several-fold increase in the accumulation of p35 mRNA. Therefore, the combined effect of LPS and IFN-γ induced sufficient expression of both p40 and p35 to attain production of the biologically active p70 heterodimer at physiologically relevant concentrations. The ratio between p40 and p35 mRNA abundance in PMN stimulated with both LPS and IFN-γ was approximately 200:1, explaining the secretion of the free p40 chain in much higher concentrations than the p70 heterodimer. IL-10, an inhibitor of the production of various cytokines in PMN, also suppressed IL-12 mRNA accumulation and secretion by PMN. Because of the important immunoregulatory function of IL-12, in particular induction of IFN-γ production and facilitation of T helper cell type 1 response, the ability of PMN to produce IL-12 suggests that neutrophils may play an active role in the regulatory interaction between innate resistance and adaptive immunity.     

Dopamine inhibition of superoxide anion production by polymorphonuclear leukocytes

To examine the modulatory effects of catecholamines on the respiratory burst in polymorphonuclear leukocytes (PMNs), dopamine was tested for its capacity to modify the superoxide anion (O2-) production by PMNs under their stimulation with several stimuli. Dopamine inhibited the O2- production by PMNs when PMNs were stimulated with N-formylated chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP), phorbol myristate acetate, or opsonized zymosan, whereas dopamine did not alter the PMN mobility. The values of percentage inhibition of the O2- production by FMLP-stimulated PMNs were 57% under treatment with 10(-5) mol/L and 83% with 10(-4) mol/L of dopamine. Isoproterenol also inhibited PMN O2- production in response to FMLP. Although a beta-adrenergic blockade, propranolol, diminished the isoproterenol-induced inhibition of the O2- production, it did not affect the inhibitory effect of dopamine. The increase in intracellular cyclic AMP levels in dopamine-treated PMNs was much smaller than the increase in isoproterenol-treated cells. Furthermore, dopamine inhibited the reduced nicotinamide-adenine dinucleotide phosphate-dependent O2- production by subcellular particles. These results indicate that dopamine inhibits PMN O2- production through its effect on PMN reduced nicotinamide-adenine dinucleotide phosphate-oxidase system rather than through its beta-adrenergic action.     

Inhibitory effect of Pseudomonas aeruginosa on the phagacytic and killing activities of rabbit polymorphonuclear leukocytes: purification and characterization of an inhibitor of polymorphonuclear leukocyte function.

A clinically isolated strain of polymorphonuclear leukocyte (PMN)-resistant Pseudomonas was found to produce an extracellular substance (PMN inhibitor) that inhibits the phagocytic and killing activities of PMN. The PMN inhibitor was purified from culture filtrates by precipitation with (NH4)2SO4 and chromatography on phosphocellulose, diethylaminoethyl-cellulose, and Sephadex G-100. The preparation was homogenous as judged by disc gel electrophoresis. The purified PMN inhibitor appeared to be a protein with a molecular weight of approximately 65,000 that was inactivated by heating and by exposure to a proteolytic enzyme.     

Interferon-gamma inhibits interleukin-8 production by human polymorphonuclear leucocytes.

Stimulation of human polymorphonuclear leucocytes (PMN) with phagocytosable particles [yeast-IgG (Y-IgG)], lipopolysaccharide (LPS), tumour necrosis factor (TNF) or formyl-methionyl-leucyl-phenyl-alanine (FMLP) results in an increase of the interleukin-8 (IL-8) mRNA accumulation and a subsequent release of the protein. Here, we report that interferon-gamma (IFN-gamma) down-regulates the constitutive IL-8 mRNA levels expressed by resting PMN. As shown by Northern analysis, this down-modulation occurred rapidly, was not dependent on new protein synthesis, and was not caused by an increased rate of degradation of IL-8 mRNA. Preincubation of PMN with IFN-gamma significantly inhibited their ability to release IL-8 upon stimulation with TNF, LPS, FMLP and Y-IgG, but enhanced the respiratory burst capability in response to FMLP and TNF. TNF-, LPS- and FMLP-induced expression of IL-8 mRNA was also selectively inhibited by IFN-gamma. Taken together these findings suggest that IFN-gamma has important regulatory effects on acute inflammatory response because of its capacity to modulate negatively IL-8 gene expression and secretion by human PMN. Further observations revealed that, in human PMN, degradation of IL-8 mRNA is finely regulated, and that cycloheximide (CHX), an inhibitor of protein synthesis, super-induces the mRNA accumulation for IL-8 in a dose- and time-dependent manner.     

Peptidoglycan and mannose-based molecular patterns trigger the arachidonic acid cascade in human polymorphonuclear leukocytes

The release of arachidonic acid (AA) in response to microorganism-derived products acting on pattern recognition receptors (PRR) was assayed in human polymorphonuclear leukocytes (PMN). Peptidoglycan (PGN) and mannan were found to be strong inducers of AA metabolism, as they produced the release of AA at a similar extent to that produced by agonists of pathophysiological relevance such as complement-coated zymosan particles and IgG immune complexes. In sharp contrast, lipoteichoic acid, LPS, muramyldipeptide, and the bacterial lipoprotein mimic palmitoyl-3-cysteine-serine-lysine-4 failed to do so. Leukotriene B4 and PGE2 were synthesized in response to mannan and PGN, thus suggesting that the lipoxygenase and the cyclooxygenase routes are operative in human PMN in response to pathogen-associated molecular patterns (PAMP). Analysis of the lipid extracts of supernatants and cell pellets as well as pharmacological studies with the calpain inhibitor calpeptin and the cytosolic phospholipase A2 (PLA2) inhibitor pyrrolidine-1 showed the dependence of AA release on cytosolic PLA2-catalyzed reactions. The effect of PGN was not inhibited by previous treatment with anti-TLR2 mAb, thus suggesting a nonarchetypal involvement of the TLR2 signaling route and/or participation of other receptors. Because of the abundance of mannose-based and PGN-containing PAMP in fungi and bacteria and the wide array of PRR in human PMN, these finding disclose a role of prime importance for PAMP and PRR in AA metabolism in the inflammatory response mediated by PMN.     

Enhancement of in vitro immunoglobulin synthesis of human lymphocytes by lysosomal enzymes from polymorphonuclear leucocytes.

The effect of human peripheral blood polymorphonuclear leucocyte (PMN) extracts and PMN granule lysates on in vitro immunoglobulin (Ig) synthesis by autologous peripheral blood mononuclear cells was studied. The mononuclear cells were cultured for 3 days with or without autologous plasma. Newly synthesized Ig in the culture supernatants was measured using 14C-labelled amino acids by an immune coprecipitation method. Upon addition of a PMN extract to plasma-free cultures Ig synthesis was stimulated, the mean stimulation index (SI) of cultures from thirteen individuals, including nine normals, three patients with rheumatoid arthritis and one with psoriatic arthritis being 1-8 +/- 0-2 in comparison with control cultures (P less than 0-05). By contrast, in 10% fresh autologous plasma, PMN extracts yielded a mean SI of 0-9 +/- 0-1 indicating inactivation of the active extracts by plasma inhibitors. In experiments using PMN granule lysates containing high concentrations of beta-glucuronidase and cultured in RPMI 1640, the mean stimulation index was 3-2 +/- 0-7. Stimulation of Ig synthesis was also produced by trypsin. Stimulation of Ig synthesis was also produced by trypsin. Stimulating factors in PMN extracts were inhibited by Trasylol, a protease inhibitor. These results indicate that trypsin and proteolytic lysosomal enzymes in PMN increase Ig synthesis of human peripheral blood mononuclear cells. They suggest a possible new role of PMN in the potentiation of immunoglobulin synthesis.     

The effects of some benzoic acid derivatives on polymorphonuclear leukocyte accumulation in vivo

Previous studies, aimed at establishing a relationship between the inhibition of prostaglandin (PG) biosynthesis and the suppression of carrageenin-induced rat paw edema, indicated that, in a series of acetylsalicylic acid (ASA)-like compounds, there is not a good correlation between ability to inhibit platelet PG biosynthesis and anti-inflammatory activity. Some of the compounds tested had good anti-edema properties compared to ASA, but did not inhibit platelet lysate conversion of 14C-arachidonic acid (AA) to PGs. The effects of these compounds on polymorphonuclear (PMN) leukocyte accumulation in urethane-anesthetized rats were examined to extend the pharmacological profile of these agents in a search for other mechanisms of anti-inflammatory activity. 3-Methylphthalide (3-MP), an inhibitor of rat paw edema, suppressed PMN leukocyte accumulation although it is a poor inhibitor of PG cyclo-oxygenase activity. 3-Propionyloxybenzoic acid (3-PBA), an agent which increases primary platelet aggregation and arterial PGI2 production, caused increases in edema formation but decreases in PMN leukocyte accumulation. 2-Propionyloxybenzoic acid (2-PBA), which is similar to ASA in many effects, resulted in a trend towards decreased PMN leukocyte accumulation, while ASA did not. 2-Acetylbenzoic acid (ABA), an agent with anti-edema properties similar to ASA in the rat paw model but without any effect on PG biosynthesis, also caused a trend towards inhibition of PMN leukocyte accumulation. In addition to drug effects on prostaglandin biosythesis, this study indicates that drug effects on PMN leukocyte accumulation is an important determinant of anti-inflammatory potential.     

Inhibition of polymorphonuclear leukocyte-mediated endothelial cell detachment by antileukoprotease: a comparison with other proteinase inhibitors

The role of elastase and proteinase inhibitors in polymorphonuclear leukocyte(PMN)-mediated injury to human umbilical cord venous endothelial cells (HUVEC) was investigated. Both purified human neutrophil elastase and PMN that were stimulated with serum-treated zymosan (STZ) induced detachment, but not lysis of HUVEC. PMN-, but not purified elastase-mediated detachment was enhanced by the presence of methionine, which indicates a role for reactive oxygen metabolites in PMN-mediated HUVEC detachment. Detachment of HUVEC could be inhibited by secretory leukocyte proteinase inhibitor or antileukoprotease (ALP), alpha 1-proteinase inhibitor (alpha 1-PI) and N-methoxy-succinyl-ala-ala-pro-val-chloromethyl ketone (CMK). At concentrations at which elastase-mediated detachment was maximally inhibited, ALP and CMK, but not alpha 1-PI, were also able to inhibit maximally PMN-mediated detachment. An explanation for this difference could be that the larger size of alpha 1-PI reduces the access of alpha 1-PI to the interface between the PMN and the HUVEC.     

Extracellular proteolysis of fibronectin by neutrophils: characterization and the effects of recombinant cytokines

We have used 125I-labeled fibronectin (FN) as an extracellular substrate for neutrophils (PMN) in order to investigate the mechanism responsible for FN solubilization by PMN and the effects of recombinant cytokines on this process. Pure active alpha 1-antitrypsin (alpha 1AT), when added to PMN before or during, but not after, adherence to FN, inhibited solubilization of the substrate in a dose-dependent manner, but alpha 1AT that had been inactivated by proteolysis or oxidation and alpha 1AT Pittsburgh (alpha 1AT 358Met-Arg) had no significant effect. The solubilization of FN was also inhibited by the PMN elastase inhibitor N-methoxysuccinyl-alanyl-alanyl-prolyl-valine-chloromethylketone but not by the chymotrypsin and cathepsin G inhibitor N-Cbz-glycyl-glycyl-phenylalanine-chloromethylketone, nor by catalase or superoxide dismutase. The products of solubilization of FN by PMN, analyzed by sodium dodecyl sulphate polyacrylamide electrophoresis, were similar to those produced by pure PMN elastase but not cathepsin G. These results suggest that FN solubilization by PMN is caused largely by the pericellular activity of PMN elastase. The solubilization of FN by PMN was increased significantly by adding tumor necrosis factor-alpha, interleukin-1 alpha, or interferon-gamma to the adherent cells but without a significant general release of elastase into the culture supernatants. Granulocyte/macrophage colony-stimulating factor (GM-CSF) had no significant effect. None of the cytokines had any effect when preincubated with the cells in suspension, and non increased FN solubilization by PMN incubated with the optimal (10(-6) mol/liter) or suboptimal dose (10(-8) mol/liter) of the peptide formylmethionylleucylphenylalanine.(ABSTRACT TRUNCATED AT 250 WORDS)     

Negative effect of a protein kinase C inhibitor (H-7) on human polymorphonuclear neutrophil locomotion.

The effects of 1-(5-isoquinoline sulphonyl)-2-methyl piperazine (H-7), a recently described inhibitor of Ca2+/phospholipid-dependent protein kinase (protein kinase C), were studied during under-agarose migration of human polymorphonuclear neutrophils (PMN) stimulated by various chemoattractants, in order to determine whether protein kinase C is involved in PMN locomotion. The effect of H-7 on the oxidative burst induced by phorbol 12-myristate 13-acetate or N-formyl-methionyl-leucyl-phenylalanine (FMLP) was also measured. Pre-incubation of PMN with H-7 concentrations ranging from 50 to 400 microM inhibited: (i) spontaneous PMN migration under agarose; (ii) the directed migration induced by activated serum, leukotriene B4 or FMLP; and (iii) the speed of the migration induced by FMLP. The inhibition by H-7 of FMLP-induced directed migration was less when FMLP was used at high concentrations which, in the absence of H-7, inhibit locomotion. H-7 depressed the oxidative burst induced by phorbol myristate acetate (PMA) but not that induced by FMLP. All the effects of H-7 on the oxidative burst and migration were reversed by washing PMN after H-7 treatment. These findings indicate that protein kinase C, inhibitable by H-7, is involved in a mechanism controlling the speed of PMN locomotion.     

Human polymorphonuclear leucocytes stimulated by tumour necrosis factor-alpha show increased adherence to extracellular matrix proteins which is mediated via the CD11b/18 complex.

The present study demonstrates that tumour necrosis factor (TNF) and FMLP, but not IL-1 or IL-8, enhanced the adherence of polymorphonuclear neutrophil (PMN) to fibronectin, an extracellular matrix protein. The adherence induced by FMLP was very rapid, within 5 min while the induction of adherence by TNF was much slower, reaching maximum at 60 min. TNF also enhanced an adhesion of PMN to other extracellular matrix proteins, such as laminin, collagen IV and gelatin II, but not to human serum albumin. Anti-CD18 MoAb completely inhibited the binding of TNF-stimulated PMN to fibronectin and partially inhibited the binding to laminin. Further investigation showed that adhesion of TNF-stimulated PMN to fibronectin and laminin was inhibited by anti-CD11b MoAb and to a lesser extent by CD11a MoAb. In contrast to TNF-stimulated PMN the binding of unstimulated PMN to fibronectin and laminin was only inhibited by anti-CD11a MoAb. Anti-CD11c had no effect on PMN adherence. These results suggest that unstimulated PMN adhere to extracellular proteins through the CD11a/18, while TNF-stimulated PMN adhere through the CD11b/18. These results suggest that TNF secreted at the site of inflammation may enhance the interaction of PMN with the extravascular environment through the CD11b/18 complex.